#W2_1_2.py
#冒泡排序法
l1 = [3,9,12,35,5,7,10]
def bb_desc(l):
    length = len(l)
    for i in range(length):
        for j in range(length - i -1):
            if l[j] < l[j+1]:
                l[j],l[j+1] = l[j+1],l[j]
    return l
l1 = bb_desc(l1)
print(l1)